On his own recordings, Pat Metheny has always pushed his artistic envelope. Very occasionally when moving to the outside, it's been to the chagrin of some fans. It happened with Ornette Coleman on the brilliant Song X in 1985; next was on the screaming guitar effort Zero Tolerance for Silence in 1994, and finally on his collaboration with Derek Bailey on The Sign of 4 in 1997. But while his collaboration with another true American original, the prolific composer John Zorn, is outside work for Metheny, it may not alienate longtime fans due to its relative accessibility. The Book of Angels is the composer's second book of compositions based on ancient, often mystical Jewish music; it contains over 300 pieces. These works have set melodies but leave plenty of room for other musicians to interpret and add to them. Other than drums -- played by Antonio Sanchez -- Metheny performs everything: guitars, orchestrion, piano, bass, bandoneon, bells, even flgelhorn. He takes Zorn's mysterious compositions and completely recontextualizes them while remaining true to them. Metheny introduces new musical ideas, myriad textural flights, and rhythmic invention to these works with a wide colorist's palette. "Mastema," with its hypnotic theme, is adorned by rock drumming from Sanchez, who handles the 11/8 signature with ease, while Metheny layers numerous countrapuntal guitars, backmasked, wailing solos, and shifting orchestrion pulses to dynamic result. Likewise, the contemplative acoustic guitars of "Albim" give way to a shimmering swing that adds tinges of tango and Brazilian music -- it wouldn't have been out of place on one of his own albums. The heart of "Tharsis" is a klezmer melody. Acoustic guitars, percussion, guitar synth, and piano display Metheny's signature euphoric interiority and balance with the inherent lyricism in Zorn's tune even as Sanchez forcefully pushes at the tempo. "Sariel" uses tiples, baritone, and high-stringed guitars to shape the melody. It's like a choir of ouds. As the piece develops, chord structures advance the sketch, and eventually Sanchez enters, adding a rock thrust. Metheny piles on electric guitars and basses to go on an extended workout, soaring with harmonic ideas and textural elements that resemble those from Italian film scores of the 1970s and '80s. No matter how unfettered his imagination runs on these pieces, neither he nor Zorn disappear. The set's closer, "Hurmiz," may raise a few eyebrows. Metheny plays piano in a duet with Sanchez that suggests free jazz, though the attention to space, form, and lyricism is inherent. Tap: John Zorn's Book of Angels, Vol. 20 is a special album in both men's catalogs. (It's being released simultaneously on both Nonesuch and Tzadik.) These compositions offer Metheny something that he's seldom been able to take advantage of. While he's regularly performed the works of other composers, he has seldom had the opportunity to so thoroughly orchestrate and arrange them. Ironically, this collaboration has resulted in giving him the freedom to explore his artistic expression as an individual, at a deeper level. ~ Thom Jurek